Lec 3 - attachment and entry Flashcards
2 things that cell needs for virus to infect it
susceptible
And permissive
What experiment provided the one step growth curve of bacteriophage T4
Ellis and Delbruck in 1939
What was multiplicity of infection used in the experiment
10 phages : 1 bact
Why did they wash and dilute the sampl
Synchronise infection
What did they use to enumerate the viral particlea
plaque assay
What happens during eclipse period and how long
Attachment, entry and uncoating
When does curve plateau
at around 100 bacteriophage = average burst size
viral cell receptor categories
protein
carbohydrate
protein receptor properties
tissue specific
(give tissue tropism)
dictate host range
carbohydrate receptor properties
less specific
HIV and measles are examples of viruses that need WHAT to get into the cell
need co receptor
name of polio recdeptor
CD155 or PVR
how was PVR discovered
panning experiment
by transfecting mouse cells with a human cDNA library.
1 polio virus interacts with how many receptors
60 receptors
VP1 at vertices forms a canyon structure,, which is where the receptor binds
what does haemagglutinin (HAbind to
-vely charged terminal sialic acid
(specifially N acetyl neuraminic acid)
what does human flu HA bind to compared to avian flu virus
human = a2-6 sialic acid (upper resp tract)
bird = a2-3 sialic acid
(lower resp tract)
3 ways for virus to get into cell
- genome injection (naked viruses)
- membrane fusion (enveloped viruses)
- endocytosis (naked viruses OR enveloped viruses and then endosome memb fusion)
in endocytosis, how is the virus taken in
via clathrin coated pit (which gets closed by dynamin)
uncoating def
process of releasing the viral genomic material so that replication can take place
diff between memb bound and naked viruses in terms of how they get their genome out
enveloped = fuses w endosome memb to get out
naked = lyses the endo from the inside
where do DNA vs RNA viruses uncoat
DNA = nuclear pore
RNA= fuses w plasma memb or endocytic vesicle memb
name of measles virus
paramyxoviridae sendai virus
what protein on measles ccell surface allows fusion to take place
fusion protein F
what receptor does measles have on it to adhere to cell surface
H protein
what kind of nucleocapsid does measles have
ribonucleoprotein (-ssRNA and viral proteins)
what condition is required for uncoatin gof influenza and why
low pH
allows M2 protein ion channel to open up
what does M2 channel allow
H+ to enter the virus
releases the attament of the viral ribonucleoprotein
which can then migrate out of the virus
what allows the viral DNA to be imported to the nucleus in influenza
nuclear location signals on genome
